improvement: make the turtle start with an offset position in lesson 4

closes #105

course/lesson-4-drawing-a-rectangle/visuals/ExampleMoveForward.tscn

@@ -10,16 +10,17 @@ var length := 200
 
 onready var _turtle: DrawingTurtle = $DrawingTurtle
 
+func _ready() -> void:
+	reset()
+
+func reset():
+	_turtle.position.x = -length / 2.0
+
 
 func run() -> void:
 	_turtle.reset()
-	_turtle.position = Vector2.ZERO
 	_turtle.move_forward(length)
-
 	_turtle.play_draw_animation()
-
-	var rect := _turtle.get_rect()
-	_turtle.position = -rect.size / 2.0
 "
 
 [node name="ExampleMoveForward" type="PanelContainer"]

course/lesson-4-drawing-a-rectangle/visuals/ExampleRectangle.tscn

@@ -11,10 +11,15 @@ var size := Vector2(200, 120)
 
 onready var _turtle: DrawingTurtle = $DrawingTurtle
 
+func _ready() -> void:
+	reset()
+
+func reset():
+	_turtle.position = -size / 2
+
 
 func run() -> void:
 	_turtle.reset()
-	_turtle.position = Vector2.ZERO
 	_turtle.move_forward(size.x)
 	_turtle.turn_right(turn)
 	_turtle.move_forward(size.y)
@@ -24,8 +29,6 @@ func run() -> void:
 	_turtle.move_forward(size.y)
 	_turtle.play_draw_animation()
 
-	var rect := _turtle.get_rect()
-	_turtle.position = -rect.size / 2.0
 "
 
 [node name="ExampleRectangle" type="PanelContainer"]

course/lesson-4-drawing-a-rectangle/visuals/ExampleRotate.tscn

@@ -13,19 +13,19 @@ onready var _turtle: DrawingTurtle = $DrawingTurtle
 
 func _ready() -> void:
 	_turtle.line_draw_speed = 200.0
+	reset()
+
+func reset():
+	_turtle.position = -Vector2(217, 57) / 2
 
 func run() -> void:
 	_turtle.reset()
-	_turtle.position = Vector2.ZERO
 	_turtle.move_forward(length)
 	_turtle.turn_right(turn)
 	_turtle.move_forward(length)
 	_turtle.turn_left(turn)
 	_turtle.move_forward(length)
 	_turtle.play_draw_animation()
-
-	var rect := _turtle.get_rect()
-	_turtle.position = -rect.size / 2.0
 "
 
 [node name="ExampleRotate" type="PanelContainer"]